The field of the invention relates to organic particle sorting and identification and more particularly to identifying and distinguishing organic particles such as microorganisms, viruses, pollen and eukaryotic cell types.
Cell sorting is a well established field and includes electrical cell analyzing devices such as disclosed in U.S. Pat. Nos. 3,924,180 and 3,946,239 to Salzman et al. and U.S. Pat. No. 4,224,567 to Hoffman. While these devices are able to discern certain characteristics about cells, they are unable to determine differences in the long range order of the genetic material among different cell types.
Some experimenters have looked at cells in suspension. Two publications, Thompson, Bottiger and Fry (Applied Optics 19, 1323 (1980)) and Hunt and Huffman, (Rev. Sci. Instrument 44 1753 (1973)) disclose experiments on cells in suspension using polarized light. The devices used in such experiments are limited to looking at a group of cells in suspension, such as 10.sup.8 viruses. Too, their light sources have only been cycled by Pockels cells driven by alternating high voltage at low frequencies, at 100 kHz maximum.
In practicing the invention, optical modulators are driven at high frequencies on the order of 40 mHz. Such high frequencies are needed to obtain information from fast moving (10 meters per second) single cells in a cell stream. A low frequency source such as of the aforementioned experiments produces too long a pulse to obtain information from a fast moving cell because the cell would not be present during the full duration of the pulse. In practicing the invention, due to rapid light cycling, fast moving cells can be analyzed one at a time and the cells can be of a variety of types whereas the Thompson et al. and Hunt et al. devices are limited to the study of suspensions of a single strain of cells.
One object of the invention is to uniquely identify a variety of bacteria, viruses, pollens and eukaryotic cells.
Another object of the present invention is to distinguish cells or organic particles in a cell stream utilizing circular intensity differential scattering and linear intensity differential scattering from the cells.
One advantage of the invention is that no staining or fixation of cells is required.
Another advantage of the instant invention is that live cells can be analyzed and sorted.